Monitoring of curing of polyurethane polymers with fluorescence method

In the present study a fluorescence technique and nine fluorescence probes have been applied to monitor the curing of polyurethanes. As the curing proceeds, the fluorescence emission bands of the probes exhibit hypsochromic shifts due to the increase in the environmental microviscosity. An intensity ratio method was developed, where ratios of the low- to high-intensity changes (LHIC) in the emission bands were used to determine the degree of the curing process. The method enables one to follow the changes in the polymer structure throughout the entire curing process and to obtain comparable results from different types of probes during the same curing process and is independent of the probes or the polymers. The technique can be applied to a variety of commercial and industrial polymers.